This invention is directed to absorbent structures, including one or more layers having differential swelling characteristics, which through controlled curvature can transform a flat planar material into one having desired shaping. The invention is also directed to absorbent articles incorporating such absorbent structures.
Absorbent articles typically include one or more absorbent layers capable of absorbing and retaining liquids. Some absorbent articles include a surge layer that is capable of quickly absorbing liquid, but is unable to retain a large quantity of liquid. A second absorbent layer having a higher absorbent capacity than a surge layer is typically located below the surge layer such that the surge layer quickly intakes liquid and subsequently passes the liquid to the more absorbent layer to retain the liquid. However, when a flat absorbent layer, such as a surge layer or a higher absorbent capacity layer, becomes saturated or is loaded too rapidly, excess liquid is likely to run off the layer in virtually any direction.
Additional components are often included in absorbent articles to further prevent the leakage of fluids from the articles. For example, certain personal care products, such as training pants, incontinence products, and diapers, often include containment flaps around the leg openings to prevent leakage at the leg openings. However, containment flaps are generally not absorbent, thus leaving the liquid free to migrate into other areas of the garment.
Molded absorbent layers are known. For example, foams may be molded into a cup-like shape, thereby directing the flow of liquid into the cup area to avoid liquid run-off. SERENITY® Guards feminine incontinence product, available from McNeil-PPC, Inc., a Johnson & Johnson Company, Milltown, N.J., U.S.A., is an example of a molded, yet non-absorbent shaped foam. However, molded foams are typically bulky and lack flexibility, thereby causing discomfort to the wearer.
There is thus a need or desire for an absorbent material that is thin and flexible in a dry state, and forms a three-dimensional concave shape when the material is sufficiently wetted, thereby directionalizing fluid flow to enhance the material's liquid-containment capability. With the concave shape, runny BM handling can be improved along with skin wellness since the concavity may be designed to create separation between the skin and the bulk of the contained fluid or BM.